There was no light here save that which filtered through the old-fashioned coloured glass of the skylight above the stair well, but Morris did not hesitate, for there was only one door to Mary Blake's apartment, the same plain white door at which, yesterday, he had knocked so long and so fruitlessly. His foot had scarcely touched the landing when his hand shot out and grasped the small brass knocker. The sharp "clap, clap," as it fell, resounded in the silence, and Donald waited. No answer. Only grave silence within and the far-away roar of the busy city without. He tried again, and yet again. Within, the silence lay unbroken. "No living thing beyond this door could fail to hear," Morris muttered to himself. "No living--oh, God! What does her letter mean?" He drew it from his pocket and looked at it, but the light was too dim. He could not decipher again its hurriedly written pages. He leaned against the edge of the door and thought as he had never thought before. The words of the letter came back to him like fire, and he clenched his teeth and groaned aloud. "What shall I do? What can I do?" he whispered to himself in an agony of apprehension--and as he leaned forward to knock once more, his eyes, grown accustomed to the dimness, caught a glimmer of something white which lay upon the threshold of the door. He dropped to his knees and touched it. He felt it to be a small portion--a corner of a scarf of soft, filmy silk, edged with fringe, fine as thistle-down. It lay across the sill, caught by the closed door. He pulled at it gently, but the door held it fast. Swiftly his hand sought and found a paper of matches in his pocket. He lit one, and as the tiny flame leapt into being he held it down toward the bit of frail silk tissue. Yes, he did recognize it. It was the scarf Mary had worn when last he had seen her. These soft folds of silk had floated against his cheek when--oh, God!--when he had kissed her. Reverently he stooped to put it to his lips--and suddenly, with a cry, he sprang to his feet. With the last flicker of the match he had seen something which brought his heart up, pounding in his ears. Wildly he struck another match, and holding the end of the scarf in his left hand, he bent and brought the wavering flame close to the place where the scarf was held by the door. Upon its pure silken folds, spreading toward him from under the door, was an ugly dried blot of an ominous, dark red. CHAPTER III PETER CLANCY Mr. Peter Clancy, early of the Metropolitan Police, late of the United States Secret Service, and currently the active head of a small but brilliant private detective agency, sat at his desk, yawning.